Cement basket and method for constructing same



May 28, 1968 J. R. SOLUM ET AL 3,385,368

EMENT BASKET AND METHOD FOR CONSTRUCTING SAME Filed Aug. 10, 1966 Afro/V514? United States Patent 01 lice 3,3353% Patented May 28, 1968 3,385,368 CEMENT BASKET AND METll-llfil) FUR (IONSTRUCTENG SAME flames R. Soium, Los Angeles, and William (I. Hempcl,

Lomita, Califi, assignors to B 8; W incorporated, Torrance, Calif., a corporation of California Filed Aug. 10, 1966, Ser. No. 571,4ti2

13 Claims. (Cl. 166-202) ABSTRACT @F THE DISCLUSURE A cement basket for use on a well pipe where a flexible frusto-conical member forms the barrier and is supported by longitudinal staves extending from a collar assembly and surrounding the member with the collar assembly comprised of a pair of concentric collars having the base of the flexible member clamped therebetween by means of expanding the inner collar beyond its elastic limit to thereby tend to expand the outer collar.

This invention relates to a device commonly known as a cementing or cement basket for mounting on the exterior of a Well pipe and positioning in a well bore to accomplish certain objectives. In particular the invention relates to a novel construction for such a cement basket and the method of accomplishing the construction.

In the completion of oil and gas wells, it is common practice to cement a well pipe in the well bore by placing the cement in the annular space between the well pipe and bore to fill and seal such annular space. In some cementing operations the cement slurry is pumped down the well pipe to the lowermost point and upwardly in the annular space. In other situations, the accepted cementing practice is to pump the cement out through a port collar opening in the well pipe intermediate its ends and then upwardly in the annular space. In either of these cementing operations it is conventional to provide one or more cement baskets along the length of the well pipe which allow the cement to flow upwardly therepast in the annular space but prevent downward flow much in the manner of the function of a check valve. For example in the port collar cementing practice, a cement basket would be positioned immediately below the port collar opening in the well pipe to prevent the cement from passing downwardly in the annular space.

Various types of cement baskets have been developed and used for these purposes and one of the most common types of cement baskets employs a canvas liner mounted within flexible staves extending upwardly and outwardly from a mounting collar on the Well pipe. The canvas liner forms the fluid tight barrier while the metal collar and staves form the support superstructure. Inherent in this arrangement is the problem of connecting the canvas liner to the metal staves and collars in a manner which is both feasible in production and supports the canvas in a destruction resistive manner. It is particularly difficult to properly connect the lower end of the canvas liner in production since the staves are normally welded to the collar. This prevents prior mounting of the canvas due to possible damage and thereafter it inhibits access to this area for the subsequent mounting of the lower end of the canvas liner. Another troublesome factor is that the assembled metal components are normally painted after welding but it is preferred that the canvas not be painted clue to the resultant stiffness, unsightliness and excessive paint used.

Accordingly it is a principal object of this invention to provide a novel cement basket construction wherein the flexible tubular liner is captured at its lower end between two concentric collars stressed to an assembled condition which may be accomplished subsequent to the welding and painting of the metal components to defectively and economically accomplish secure mounting of the lower end of the flexible liner.

Another object of this invention is to provide a novel cement basket wherein the mounting collar is comprised of a pair of concentric collars expanded with the base of the tubular liner positioned therebetween both to secure that portion of the liner and properly size the inner collar for fitting the exterior of the well pipe.

Other and more detailed objects and advantages of this invention will appear from the following description and the accompanying drawings, wherein:

FIGURE 1 is a perspective view of the cement basket of this invention.

FIGURE 2 is a sectional elevation of one side of the cement basket taken substantially on the line 2-2 in FIGURE 1 through one of the staves.

FIGURE 3 is a composite sectional plan view taken through the mounting collar illustrating the relationship of the components before assembly in the left-hand portion and after assembly in the right-hand portion.

FIGURE 4 is a sectional view taken substantially on the line 4-4- of FIGURE 2 and illustrating the cross section of each stave.

Referring now in greater detail to the drawings, the cement basket of this invention is generally designated 10 and is comprised of a collar assembly 11, a plurality of staves 12 and a flexible tubular element or liner 13. The collar assembly 11 is comprised of an inner collar 14 and an outer collar 15 of approximately the same axial length and assembled in the manner hereinafter described.

The plurality of staves 12 are positioned around the circumference of outer collar 15 and may be abutting one another or spaced circumferentially such as the slight spacing shown. The lower ends 16 of the staves 12 are secured to the outer collar 15 by any convenient means such as welding 17. When welding is used to secure the staves 12 to the collar 15 this is accomplished as one of the first assembly steps without the tubular element 13 being present since such element may be flammable or at least subject to damage due to the welding. Each stave 12 extends upwardly and outwardly from collar 15 whereby the aggregate of the plural staves 12 define a cage with a circle formed by their outermost portions 18 of a diam eter approximately equal to the well bore diameter in which the cement basket will be positioned. It is to be noted that the staves 12 may actually be of a configuration for the portions 18 to tend to extend outwardly to an even greater diameter but such will be restrained by the tubular element 13 as will appear hereinafter. Each of the staves 12 preferably has an upper end 19 extending upwardly beyond the portion 18 and curved inwardly a short distance to avoid catching on the wall of the well bore or casing joints through which the cement basket is past. The staves are of a resilient material such as spring steel so that the staves will fiex inwardly but will resume their original shape. For added beam strength each of the staves 12 are curved in cross section as shown in FEGURE 4. This permits the use of rather thin sheet metal and in this regard sheet steel of .078 inch thickness has been found adequate.

The aggregate of the assembled staves 12 on the collar 15 form a cage or superstructure of a generally frustoconical shape. This assemblage may be given its final finishing coat of paint or the like since none of the subsequent assembly operations wiil adversely atfect such finish.

A flexible tubular element 13 is provided as the fluid barrier in the cement basket 10 and, as shown in the drawings, this element will normally be comprised of a heavy canvas or the like. The canvas of tubular element 13 is sewn into a tapered tubular or frusto conical shape to fit within the cage formed by the plurality of upstanding staves 12. The upper end of tubular element 13 is provided with a hem 20 sewn at 21 to increase the circumferential strength of the element and prevent tearing. The hem portion 20 of tubular element 13 is positioned at the outermost portions 18 of the staves 12. Each stave 12 is fixed to the tubular element 13 at the hem 20 by any convenient means such as rivet 22 passing through preformed holes in the staves 12 and element 30. The circumference of tubular element 13 at hem 20 is approximately the circumference of the well bore and since the staves are connected to the hem 20 they are restrained in this configuration as previously mentioned.

The lower end 23 of the tubular element 13 is of approximately the diameter of the collar assembly 11 and is secured thereto in the following manner. Outer collar 15 is originally formed having a diameter slightly less than the final diameter desired for such collar. The inner collar 14 is originally formed to a diameter less than the desired final diameter of collar 14 which must fit the well pipe on which the cement basket will be used. The difference in the respective original and final diameters of the collars is even greater for collar 14 than for collar 15. The lower end 23 of the tubular element is positioned between collars 14 and 15 as shown in the left-hand portion of FIGURE 3. Collar 14 is then expanded radially to capture the tubular element lower portion 23 between the outer surface of inner collar 14 and the inner surface of outer collar 15. The expansion of collar 14 is continued beyond the elastic limit of collar 14 and until outer collar 15 has also been expanded slightly and is subjected to high hoop tension thereon. The expanding forces are released whereupon outer collar 15 contracts about inner collar 14 which has been permanently deformed to a larger diameter and such hoop tension contracting forces subject inner collar 14 to compression forces. These equal and opposite forces between inner collar 14 and outer collar 15 securely clamp the lower portion 23 of the tubular element 13 therebetween as shown in the right-hand portion of FIGURE 3. By preselecting the original diameters of collars 14 and 15, the final resultant inside diameter of collar 14 may be sized perfectly to fit the particular size of well pipe on which it will be mounted. The radial expansion of the collars may be accomplished by any convenient conventional means such as expanding mandrels comprised of plural segments of a circle forced outwardly in an equal manner. It is to be noted that this assembly of collar 14 and collar 15 to secure the canvas is accomplished without welding or any other process which would damage the canvas of the tubular element or require repainting of the collars 14 and 15. This completes the cement basket if the rivets 22 have been previously installed as described.

By way of illustrative example and without intending to limit the scope of this invention, the formation of collar assembly 11 has been successfully accomplished by using twelve gauge steel for the collars 14 and and flash weldring these in their annular shape. For a cement basket to fit a 5 /2 inch diameter well pipe wherein the inside diameter of collar 14 will be slightly over 5 /2 inches, it has been found to be satisfactory to provide collar 14 with an original diameter that will be increased by about /8 of an inch in the final assembly and to provide a collar 14 which is of an original outside diameter one-quarter inch smaller than the inside diameter of collar 15. This difference in size of collars 14 and 15 provides about inch annular gap between the collars for accommodating the lower end 23 of the tubular element before expansion of the collars. Further this assures that a substantial expansion of collar 14 which is required will accomplish permanent deformation (expansion) of the collar by exceeding the elastic limit of the material.

Thus it may be seen that by this construction a cement basket is formed which @Qmbines a minimum number of components in an effective and economical manner and is susceptible to high production techniques. The lower end of the flexible tubular element is secured to the mounting collar with a permanency not heretofore accomplished. The upstanding staves provide the needed structural support for the flexible tubular element and yet do not interfere with the mounting of the lower end of the tubular element. Further, the finishing technique such as painting is greatly simplified by permitting the accomplishment thereof before installation of the canvas tubular element. While a particular embodiment of this invention has been shown and described, it is to be understood that the invention is not limited to the details shown and described but rather is of the full scope of the appended claims.

We claim:

1. In a cement basket adapted to be mounted on a well pipe, the combination of, inner and outer concentric and continuous collars assembled with the inner collar adapted to fit the well pipe, a plurality of staves mounted on said outer collar and extending outwardly and upwardly, a flexible tubular element positioned within said staves, said tubular element having a lower end positioned between said pair of concentric collars, and said collars both forcea'bly stressed and strained circumferentially in the same direction with one of said collars stressed beyond its elastic limit causing a permanent strain therein tending to make that one collar approach the circumferential size of the other collar and thereby causing circumferential tension stress in said outer collar and compression stress in said inner collar with such opposing stressed condition clamping the tubular element therebetween.

2. The cement basket of claim 1 wherein said inner and outer collars remain assembled solely by the opposed stress forces with said inner collar tending to expand and said outer collar tending to contract.

3. The cement basket of claim 1 wherein each said collar is a thin metal band and said inner collar is expanded beyond the elastic limit of the metal to increase the nominal size of the inner collar and expand the outer collar.

4. The cement basket of claim 1 wherein said collars are expanded with the tubular element therebetween and the inner collar is stressed beyond the elastic limit thereof and causes expansion of the outer collar.

5. The cement basket of claim 1 wherein circular steel bands are the inner and outer collars with the outer colhr of an original diameter slightly less than the diameter thereof in the assembled condition and the inner collar of an original outside diameter slightly smaller than the original inside diameter of the outer collar for accommodating said tubular element, the staves are steel with an arcuate cross-section and welded to the outer collar, said collars are expanded with the tubular element therebetween and the inner collar is stressed beyond the elastic limit thereof and causes expansion of the outer collar.

6. The cement basket of claim 5 wherein the tubular element is connected at its upper end to each stave by riveting.

7. In a cement basket adapted to be mounted on a well pipe, the combination of, inner and outer concentric and continuous collars assembled with the inner collar adapted to fit the well pipe, a plurality of staves circumferential spaced about and mounted on said collar, said staves extending outwardly and upwardly for engaging the well bore wall and forming a cage of frustro-conical shape, a frustro-concial tubular element of flexible fabric positioned within said staves and generally conforming to said cage shape, said tubular element having an upper end connected to the outward most portions of said staves, said tubular element having a lower end positioned between said pair of concentric collars, and said collars both forceably stressed and strained circumferentially in the same direction with one of said collars stressed beyond its elastic limit causing a permanent strain therein tending to make that one collar approach the circumeferential size of the other collar and thereby causing circumferential tension stress in said outer collar and compression stress in said inner collar with such opposing stressed condition for securing the tubular element between the collars and maintaining the collars in assembly with said outer collar in tension encircling said inner collar and said inner collar in compression supporting said outer collar.

8. The cement basket of claim 7 wherein each said collar is a thin metal band and said inner collar is expanded beyond the elastic limit of the metal to increase the nominal size of the inner collar and expand the outer collar.

9. The cement basket of claim 7 wherein said collars are expanded with the tubular element therebe-tween and the inner collar is stressed beyond the elastic limit thereof and causes expansion of the outer collar.

10. A cement basket adapted to be mounted on a well pipe, such cement basket including a mounting collar for fitting the well pipe, a plurality of resilient staves mounted on the exterior of the mounting collar and extending in an axial and outward direct-ion, and a flexible tubular element mounted within and to said staves to form a frustroconical barrier, the improvement comprising, two concentric inner and outer continuous collars comprising said mounting collar, said flexible tubular element having a lower portion positioned between said inner and outer collars, and said collars both forceably stressed and strained circumferentially in the same direction with one of said collars stressed beyond its elastic limit causing a permanent strain therein tending to make that one collar approach the circumferential size of the other collar and thereby causing circumferential tension stress in said outer collar and compression stress in said inner collar with such opposing stressed condition for securing the tubular element therebetween and maintaining the collars in assembly with said outer collar in tension encircling said inner collar and said inner collar in compression supporting said outer collar.

11. An improved method of constructing a cement basket adapted to be mounted on a well pipe, which basket is normally made by forming an annular mounting collar for fitting the well pipe, mounting a plurality of resilient staves on the collar for extending in an axial and outward direction, and forming and mounting a flexible tubular element within and to said staves and to the exterior of the collar to form a conical barrier, the improvement in the method comprising, forming two concentric annular rings for comprising said collar, positioning a portion of said flexible tubular element between the pair of concentric rings, and expanding the inner of said pair of rings beyond its elastic limit to secure the element between said rings.

12. The method of constructing a cement basket, comprising, forming a pair of metal collars with one collar smaller than the other, mounting a plurality of resilient staves on the exterior of the larger collar to extend both outwardly and longitudinally in one direction, forming a flexible tubular element to fit within the plural staves, positioning the lower end of said element between said two collars, and expanding the smaller collar beyond its elastic limit to a diameter suflicient to cause expansion of the larger collar for clamping the tubular element therebetween and sizing the smaller collar to fit the well pipe on which the cement basket is to be mounted.

'13. The method of claim 12 in which the smaller collar and assembled staves and larger collar are coated with a final surface finish before the step of inserting the tubular element between the collars.

References Cited UNITED STATES PATENTS 1,329,762 2/1920 Guy 29-446 2,029,380 2/1936 Manning 16626 2,248,908 7/1941 Phil-lips 166154 X 2,460,561 2/1949 Winkel-mann 166202 X 2,479,702 8/1949 Rood 29523 X 2,652,118 9/1953 Hartman et a1. 166202 2,922,478 1/1960 Maly 166154 2,969,839 1/1961 Greene 166-117 3,055,095 9/1962 Barry 166187 X 3,140,535 7/1964 Pechacek 29523 X CHARLES E. OCONNELL, Primary Examiner.

I. A. CALVERT, Assistant Examiner. 

